Herbicidal auxenic compounds have been used for many years to control broadleaf noxious weeds without damage to desirable grasses infested with the weeds. 2,4-D, 2,4-DP, 2,4-DB, MCPP, MCPA, MCPB, which are exemplary herbicidal auxinic compounds, have all been registered and long used individually or in combination as herbicides for treating turf to control undesirable broadleaf vegetation without significantly adversely affecting desirable grasses. Similarly, herbicidal protox inhibitors such as carfentrazone-ethyl, sulfentrazone, and pyraflufen-ethyl have in recent years been used to control undesirable broadleaf vegetation. Although auxinic and protox inhibitor compounds as described have individually been found to be effective in broadleaf weed control without significant damage to desirable grasses, these compounds have not been known to be effective for control of grassy weeds, such as crabgrass, goosegrass and dahlisgrass.
Thus, there continues to be a need for increasing the herbicidal effectiveness of exemplary herbicidal protox inhibitors and herbicidal auxinic compounds, which have heretofore been used alone or in combination, and especially to provide a herbicidal composition that will not only control noxious broadleaf vegetation, but also be effective against grassy weeds without adversely effecting desirable grasses. The urgency of the need is exacerbated by increasing governmental oversight of the sale and approved use rate of herbicidal materials. The recommended level of herbicide that may be applied per unit of area is under pressure from governmental, as well as for economic and environmental reasons.
In addition, certain species of undesirable broad leaf vegetation and grassy weeds are becoming more and more resistant to a number of the most widely used herbicides. Thus, on one hand ever more stringent conditions are being placed on the type and use rate of herbicides, while on the other hand accepted herbicides are becoming less and less effective over time in certain species of noxious weeds.
Furthermore, it is very expensive and time consuming to seek and obtain registration of a new herbicidal compound, including its proposed use rate. Approval data required must not only include evidence of efficacy at the application rates proposed but also the safety of the herbicide when applied at the recommended level.
Accordingly, demonstration of synergism by the combination of existing herbicidal agents, permits use of the individual components of the synergistic combination at lower rates than when used alone, and in many instances ameliorates increasing resistance to herbicidal effectiveness.
Accordingly, there is a great need for improved broadleaf and grassy weed control compositions and a method of controlling such noxious vegetation without adversely affecting desirable plants and which reduces the amount of chemical herbicidal agent necessary to obtain the acceptable weed control.